Pump assembly



Feb. 25, i969 v. H. B. wlLHn-E PUMP ASSEMBLY Shes-2'(l Filed June 19, 1967 v. H. B. wlLHlTE PUMP AS SEMBLY Filed June 19, 1967 V. H. B. WILHITE PUMP ASSEMBLY Fei). 25, i969 Sheet Filed June 19. 1967 United States Patent O 3,429,272 PUMP ASSEMBLY Verbon Henry Bryce Wilhite, 179 North Sth East, Brigham City, Utah 84302 Filed .lune 19, 1967, Ser. No. 647,020 U.S. Cl. 103 148 19 Claims Int. Cl. F04b 43/06, 43/10 ABSTRACT OF THE DISCLOSURE This invention relates to a pump assembly including a bladder dening a central chamber for receiving material. The bladder has a side wall which is relatively exible adjacent to a first end portion of the bladder and is relatively inflexible adjacent to a second end portion of the bladder. When hydraulic pressure is applied against the side wall of the bladder, the relatively flexible first end portion of the bladder collapses before the relatively intiexible second end portion of the bladder to force material in the central chamber of the bladder from the first end portion of the bladder and out an opening in the second end portion of the bladder.

Concrete slurry and other fluid materials are often moved with piston type pumps. These piston type pumps have a large number of working parts and are relatively expensive to manufacture and maintain. The expense of maintaining prior art piston type pumps is substantially increased when the pumps are used for handling heavy, wear-inducing materials such as concrete slurry. Therefore, it is an object of this invention to provide a pump assembly which overcomes the aforementioned shortcomings of prior art constructions. Specifically, it is an object of this invention to provide an inexpensive pump structure which has relatively few moving parts and is easy to maintain.

Another object of this invention is to provide a pump assembly including .a bladder which is relatively exible adjacent to a first end portion and relatively inflexible adjacent to a second end portion so that the bladder is collapsed with a wave moving from the first end portion of the bladder to the second end portion of the bladder to expel materials from the second end portion of the bladder.

These and other objects and features of the invention will become more apparent upon a reading of the following detailed description taken in connection with the accompanying drawings wherein:

FIG. 1 is a plan view of a pump assembly forming a preferred embodiment of the invention, the pump assembly including a central longitudinally extending body portion, a valve assembly at either end of the body portion for controlling the flow of liuid into the body portion, and a plurality of hydraulic piston and cylinder assemblies mounted radially outwardly of the central body portion;

FIG. 2 is an enlarged cross-sectional view, along the line 2 2 of FIG. 1, illustrating the structure of the central body portion which includes a rigid shell surrounding a perforated liner within which a exible bladder is mounted, the bladder being shown in solid lines in a normal or initial position and in dashed lines in a partially collapsed position;

FIG. 3 is an enlarged sectional view, taken along the line 3 3 of FIG. 2, further illustrating the interrelationship of the shell, liner and bladder;

FIG. 4 is an enlarged plan View of the bladder illustrating the side wall of the bladder which includes a plurality of ribs which taper from a relatively small crosssection at the right or input end of the bladder to a relatively large cross-section at the left or output end of the bladder;

3,429,272 Patented Feb. 25, 1969 FIG. 5 is an enlarged cross-sectional view of the bladder, taken along the line 5 5 of FIG. 4, illustrating the structure of the side wall of the bladder and showing the relatively small cross-section of the ribs at the input end portion of the bladder, the bladder being shown in solid lines in the initial or normal position and in dashed lines in the collapsed position;

FIG. 6 is an enlarged cross-sectional view similar to FIG. 5 and is taken along the line 6 6 of FIG. 4;

FIG. 7 is an enlarged crosssectional view, taken along the line 7 7, further illustrating the structure of the side wall of the bladder and showing the relatively large cross-section of the ribs at the output end portion of the bladder;

FIG. 8 is a cross-sectional view, on a reduced scale, of a second embodiment of the invention wherein the bladder side wall includes longitudinally extending ribs in which spring elements are mounted or embedded;

FIG. 9 is an enlarged cross-sectional view further illustrating the structure of the side wall of the second embodiment of the bladder;

FIG. 10 is an enlarged cross-sectional view illustrating a tapered side wall of a third embodiment of the bladder;

FIG. 11 is an enlarged cross-sectional view illustrating another embodiment of the pump assembly wherein coil springs are utilized to control the collapsing of the -bladder;

FIG. 12 is an enlarged cross-sectional view, taken along the line 12 12 of FIG. 11, further illustrating the structure of the pump assembly of FIG. 11;

FIG. 13 is an enlarged cross-sectional view, similar to FIG. 11, of an embodiment of the pump assembly Wherein leaf springs are utilized for controlling the collapsing of the bladder;

FIG. 14 is an enlarged cross-sectional view, taken along the line 14 14 of FIG. 13, further illustrating the structure of the pump assembly of FIG. 13; and

FIG. 15 is a partial sectional view of still another embodiment of the pump assembly wherein a plurality of unevenly spaced leaf springs are utilized for controlling the collapsing of the bladder.

Referring now to the drawings in greater detail, a pump assembly 20` forming a preferred embodiment of the invention is shown in FIG. 1. The pump assembly 20 is operated to move concrete slurry and other materials along a pipe or conduit line including a iirst or input conduit 22 (shown at the far right of FIG. l) and a second or output conduit 24 (shown at the far left of FIG. l). Although the pump assembly 20 has been shown in FIG. 1 for moving uid materials along a horizontally extending conduit line, it is apparent that the orientation of the pump assembly can be changed to move the concrete slurry and other fluids along upwardly extending conduit lines. The pump assembly 20 includes a central body portion 26 mounted in a coaxial relationship with the conduits 22 and 24. Materials pass through the body portion 26 in flowing upstream from the conduit 22 to the conduit 24. An input valve assembly 30 is provided adjacent to the input conduit section 22 for controlling the flow of tiuid from and into an input portion or downstream end 34 of the body section 26. Similarly, an output valve assembly 36 is connected to the output conduit 24 and an output portion or upstream end 40 of the body section 26 to control the flow of fluid between the conduit 24 and the output end portion 40 of the pump assembly. A plurality of double acting hydraulic piston and cylinder assemblies 44 are mounted with their longitudinal axes extending parallel to the longitudinal axis of the body section 26. The piston and cylinder assemblies are connected to a radially or transversely extending manifold or head assembly 48 which is in fluid communication with the interior of the body section 26.

The body section 26 of the pump assembly 20 is shown in greater detail in FIG. 2. The body section of the pump assembly includes a longitudinally extending steel shell or outer casing 52 and a longitudinally extending perforated steel liner or spacer 54. The liner 54 is located radially inwardly from and coaxially with the shell 52 to provide an annular longitudinally extending passage 56 between the shell 52 and liner 54. A flexible bladder y60 is mounted radially inwardly of and coaxially with the liner 54 and is formed of an elastomeric material. The bladder 60 defines a central longitudinally extending material receiving chamber `62 which is connected in fluid communication with the input conduit 22 and output conduit 24 through openings in the input end portion 34 and output end portion 40 of the bladder 60. An initial or normal position of the bladder 60 is shown in solid lines in FIG. 2. Hydraulic pressure against an outer surface 64 of a side wall -66 of the bladder causes it to move or collapse radially inwardly from the initial position to a collapsed position shown in dashed lines in FIG. 2. When the bladder moves from the initial position to the collapsed position, concrete slurry or other material within the chamber 62 is expelled from the bladder in a pumping action.

During operation of the pump assembly the chamber 62 is first filled with fluid material from the conduit 22 while the value assembly 36 is closed and the valve assembly is open. The valve assembly 30 is then closed and the valve assembly 36 is opened to allow the fluid material to flow out of the pump assembly in only an upstream direction, that is toward the output conduit 24 and away from the input conduit 22. The hydraulic piston and cylinder assembly 44 is then actuated to move pistons 70 in cylinders 72 to force fluid under pressure from the cylinders 72 into the manifold 48. This high pressure fluid flows from the manifold 48 through the longitudinally extending annular passage 56 and apertures 76 in the liner 54 to engage the radially outer surface `64 of the bladder 60. As the fluid pressure is increased by the piston and cylinder assemblies 44, the bladder 60 is moved from the initial or normal position to the collapsed position to expel fluid material from the inner chamber or cavity 62. Since the valve assembly 30 is closed to block the flow of material in a downstream direction, the material in the cavity 62 is expelled from the output end portion of the body section 26, through the valve assembly 36 and into the output conduit 24. The valve assembly 36 is then closed and the valve assembly 30 opened.

After the valve assembly 30 has been opened, the pistons 70 of the double acting piston and cylinder assemblies y44 are moved back to their initial position (as shown in FIG. l). This reverse movement of the pistons 70 draws the fluid from the passage 56 and manifold 48 back into the cylinders 72. As the fluid is withdrawn from the body section 26- of the pump assembly, the bladder 60 expands to the normal position and draws or sucks materials from the input conduit 22 into the cavity 62 to refill the cavity with fluid materials. The pump assembly 20 is then ready for a second cycle of operation which begins by closing the valve assembly 301 and opening the valve assembly 36. Repetition of this operating cycle collapses and expands the bladder 60- with a generally systolic action to pump a pulsing flow to fluids from the conduit 22 to the conduit 24.

As perhaps can be best seen from a comparison of FIGS. 2 and 3, the liner 54 has a generally annular cross-section and extends around the bladder 60 to provide the continuous passage 56 between the liner 54 and the shell 52. The passage 56 is connected to the manifold 48 and insures that fluid flows for substantially the entire length of the body section 26 to enable fluid pressure to be exerted against the entire outer surface 64 of the bladder 60. This fluid pressure against the outer surface of the bladder results in a uniform movement of the bladder from the -initial position to the collapsed position l(see FIGS. 1 and 2). If the liner 54 and passage 56 were omitted, the bladder would rest against the liner 52 and would tend to block the flow of fluid along one side of the bladder. Fluid pressure could not then be exerted on all sides of the bladder and an uneven collapsing of the bladder would occur. This uneven collapsing of the bladder 60 would be promoted by the weight of the fluid materials within the chamber 62 in the bladder which would press the bladder downwardly against the shell 52.

The bladder 60 is shown in greater detail in FIG. 4. The side wall 66 of the bladder 60 includes a plurality 0f longitudinally extending reinforcing ribs or ridges 8i) which are interconnected by arcuate webs or side sections 82 extending between the ribs for substantially the entire length of the bladder 60. From an inspection of FIGS. 5 through 7, it can be seen that the side sections 82 are of a uniform thickness throughout the entire length of the bladder. The ribs are also of uniform thickness throughout the entire length of the bladder. However, the ribs are tapered from a relatively small cross-section at a frusto-conical downstream or input end portion 86 of the bladder to a somewhat larger or intermedi-ate size at a cylindrical central portion 88 of the bladder and finally to a relatively large width at a frusto-conical downstream or output end portion 90 of the bladder. This uniform tapering width of the ribs 80 is best seen by a comparison of FIGS. 5 through 7.

At the input end portion 86 the ribs are relatively narrow in width and provide little reinforcing for the bladder so that the input end portion 86 of the bladder is quite flexible. Both the width and reinforcing action of the ribs are substantially larger at the central portion 88 of the bladder 60, as is best seen in FIG. 6. From an inspection of FIG. 7, it can be seen that the ribs are quite wide at the output end portion 90 of the bladder so that the outuput end portion 90 is relatively inflexible when compared to the input end portion 86 of the bladder. Since the rigidity of the bladder increases toward the Output end portion 90, the input end portion 86 of the bladder is moved from the initial position to the collapsed position by fluid pressure before the output end portion 90 of the bladder is collapsed. This increasing rigidity or decreasing flexibility results in the bladder 86 collapsing in a w-ave type action which moves from the input end portion 86 of the bladder toward the output end portion 90 of the bladder when fluid pressure is applied against the bladder. It will be appreciated that reinforcing ribs 80 of a shape `other than the preferred shape shown can be used for giving the bladder the requisite flexibility characteristics. For example, the ribs could have both a tapering width and thickness or just a tapering thickness.

This wave type collapsing action is promoted by the shape of the bladder 60. The bladder 60 is relatively short and frusto-conical in shape at the input end portion 86 to provide a relatively large spacing between the ribs 80. In addition, the side wall 66 has a comparatively sharp slope to maximize an upstream component of pressure force on the bladder. The elongated frusto-conical shape of the output end portion 90 results in the ribs 80 being spaced close together at the upstream end portion of the bladder to maximize rigidity. The wave type collapsing action is also promoted by the application of uniform fluid pressure throughout the entire length of the bladder. The uniform application of increasing fluid pressure on all sides of the bladder 60 results in the relatively llexible input portion 86 collapsing first, the somewhat lmore rigid or inflexible central portion 88 collapsing second and finally the relatively inflexible output end portion 90 collapses. This wave type collapsing of the bladder 60 eliminates any possibility of trapping materials within the bladder and results in a forcing of materials from the input end portion 86 toward the central portion 88 and finally out the output end portion 90 of the bladder. This wave type collapsing of the bladder 66 gives a generally peristaltic action as the pump assembly 20 is operated through a series of cycles.

A modified embodiment of the bladder 60 is shown in FIGS. 8 and 9. Since the components of the modified form of the bladder are substantially the same as the bladder 60, the same numerals have been used to designate the modified form of the components of the bladder of FIGS. 8 and 9 with the suffix letter a being used to distinguish the components of FIGS. 8 and 9 from the components of FIGS. 1 through 7. The bladder 60a of FIGS. 8 and 9 includes a plurality of longitudinally extending ribs 80a which are of uniform width and thickness. The reinforcing action of the ribs 80a is varied by the embedding or mounting of spring members 94 in the ribs 80a, as is perhaps best seen in FIG. 9. The spring members 94 do not extend for the entire length of the bladder 60. Rather, the spring members extend from the output end portion 90 into the central portion 88 of the bladder 60. Therefore, the input end portion of the bladder 86 is relatively flexible while the output end portion 90 of the bladder is relatively inexible due to the resilient reinforcing action of the spring members 94. It is contemplated that the dimensions of the spring member 94 can, if desired, be varied to increase the rigidity of the spring members toward the output end portion 90 of the bladder.

A third embodiment of the bladder is shown in FIG. 10 `wherein the components of the bladder have been designated with numerals similar to those used in connection with FIGS. 1 through 7 with the sul-hx letter b being used to distinguish the components of the bladder of FIG. 10 from those of FIGS. 1 through 7. The bladder 60h of FIG. 10 does not, in the preferred form, have longitudinally extending ribs. However, the side wall 66b of the bladder 6012 is tapered from a relatively small thickness at the input end portion of the bladderl to a relatively large thickness at the output end portion of the bladder. This tapering of the wall 66b, which is exaggerated for purposes of clarity of illustration in FIG. 10, provides the requisite flexibility characteristics so that the bladder 6619 is collapsed in a wave which begins at the relatively flexible input end portion 86 of the bladder and moves toward the relatively inflexible output end portion 90 of the bladder. Of course, the side wall 66b could in clude reinforcing ribs, similar to the ribs 80.

A plurality of embodiments of the pump assembly are shown in FIGS. 11 to 15 wherein externally mounted springs are utilized for varying the flexibility of the bladder. Since these embodiments of the pump assembly are generally similar to the embodiments of FIGS. 1 through 10, similar numerals have been used to designate the components of these embodiments with the suffix letter c being used to distinguish the components of FIGS. 11 and 12; the suffix letter d to distinguish the components of FIGS. 13 and 14; and the suffix letter e to distinguish the components of FIG. 15. Referring now to the embodiment of the pump assembly c shown in FIG. 1l, a generally cylindrical steel shell or casing 52C extends circumferentially around a ribbed bladder 60C to define a central longitudinally extending material receiving chamber 62C. A plurality of coil springs 100 are mounted in a longitudinally extending annular passage 56e formed between the bladder 60C and the shell 52C. The springs are tixedly connected at one end to the shell 52C, as shown in FIG. 12, and at the other end to the ribs 80C of the bladder 60C. As can be best seen in FIG. 11, the springs are mounted in groups including a rst spring group 102 of four springs which are spaced ninety degrees apart. The number of springs in the spring groups increases in an upstream or inward direction so that a spring group 104 adjacent to the spring group 102 includes eight springs mounted in pairs at ninety degree intervals around the bladder. A t-hird spring group 106 of twelve springs, a fourth spring group 108 of sixteen springs, and a fth spring group 110 of twenty springs are sequentially mounted between the bladder and shell 52, as shown in FIG. 11. The sp-rings 0f each of the spring groups 102 through are substantially the same in structure so that the resistance to collapsing of the bladder increases in an upstream direction with the increasing number of springs in the spring groups. Therefore, the Ibladder has the least resistance to collapsing, or the greatest exibility, adjacent to the input end portion 34C where the spring group 102 holds the bladder in the position shown in FIG. 11. Of course, the resistance of the bladder to collapsing increases in a downstream direction as the number of springs in a spring group increases. Thus, the progressively increasing spring groups provide the bladder with the requisite resiliency to have a wave type collapsing action which extends from the input end portion 34C of the bladder toward the output end portion when hydraulic pressure within the passage 56C is increased.

In the embodiment of the invention set forth in FIGS. 13 and 14, leaf springs 114 are mounted exteriorly of a bladder 60d between the ribs 80d of the bladder and the shell or casing 52d. The arcuate leaf springs 114 are mounted in a plurality of groups of four springs each, as indicated at 116, 118, and 122 in FIG. 13. The leaf springs 114 of the rst or downstream spring group 116 have a relatively small cross-section. However, the crosssection of the springs of each spring group increases in an upstream direction so that the springs of the spring group 118 have a cross-section which is somewhat larger than the cross-section of the springs -of the spring group 116. Similarly, the springs of the spring group 120 have a larger cross-section than the springs of the spring group 118 and the springs of the spring group 122 have `a still larger cross-section. This progressively increasing crosssectional size of the spring groups provides an increasing stiffness or resistance to deformation 0f the bladder 60d so that the bladder 60d collapses in a wave-type action from the input end 34d of the bladder toward the output end of lthe bladder 60d. Of course, if desired, the springs of each spring group could have the same cross-sectional size and the number of springs in the spring groups could be sequentially increased in the upstream direction in order to provide the requisite resiliency characteristics for the Ibladder 60d, in a manner similar to that disclosed in the embodiment of FIGS. 11 and 12.

In the embodiment ofthe invention set forth in FIG. 15, a plurality of spring groups 124 through 134 have been provided for supporting the bladder 60e in a spaced apart relationship relative to the shell 52e. From an inspection of FIG. 15 it can be seen that the spring groups are spaced lprogressively closer together toward the downstream end of the bladder 60e. Thus, the spring group 126v is spaced a relatively large distance from the spring group 124 while the spring group 128 is spaced a somewhat smaller distance from the spring group 126. The distance between the spring groups is gradually decreased so that the spring group 134 is fairly close to the spring group 132. This decreasing distance between the spring groups in the upstream direction results in an increasing resistance to deformation of the bladder 60d in the upstream direction to provide the previously explained wave-type collapsing action.

In view of the embodiments of the invention set forth in FIGS. 11 through 15, it is apparent that the bladder of the pump assembly can be given the requisite flexibility characteristics by externally mounted springs. The springs being varied in size, number, spacing or a desired combination of these characteristics provide the bladder with a relatively flexible input portion and a relatively inexible output portion. It should be noted that the provision of springs mounted between the outer shell and the bladder eliminates the necessity of providing a perforated liner, similar to the liner 54 of FIG. 1, for holding the bladder in a spaced apart relationship with the shell.

For purposes of affording a more complete understanding of the pump assembly 20, it is advantageous now to provide a functional description of the mode in which the component parts thus far identified cooperate. The central chamber 62 of the bladder 60 is initially filled with a uid material, such as concrete slurry. Fluid pressure is then applied against the outer surface 64 of the side wall 66 of the bladder. Since the bladder is relatively liexible adjacent to the input end portion 86, the input end portion will collapse before the central portion 88 and output portion 90. After the input portion 86 has collapsed, the central portion will collapse and finally, the output end portion 90, which is relatively inflexible, will collapse. This wave-like collapsing of the `bladder 60 insures that material is expelled out of the output end portion 90 of the bladder and is not trapped in either the input end portion 86 or lcentral portion 88 of the bladder.

Turning once again to a consideration of FIG. l, the valve assemblies and 36 are substantially identical in construction. The valve assembly 30 includes a flexible conduit section 100 which is connected to the input end portion 34 of the pump assembly 20. The flexible conduit 100 is squeezed together or constricted by a pair of rollers 102 and 104 to prevent the passage of material through the conduit 100 when the valve assembly 30 is in the closed position shown. The rollers 102 and 104 are mounted on third class levers 106 and 108 for pivoting movement from the closed position in which the valve 30 is shown to the open position in which the valve assembly 36 is shown. The levers 106 and 108 of the valve assembly 30 are moved from the closed position to the open position and back again by a double acting piston and cylinder assembly 110. During this pivoting movement, forces are transmitted between the levers 106 and 108 by meshing gear segments 112 and 114. The gear segments 112 and 114 also coordinate the movement of the levers 106 and 108 so that both levers are pivoted contemporaneously from the open to the closed position and from the closed to the open position.

The levers 106 and 108 are mounted for pivoting movement about pivot pins or axes 118 and 120` It should be noted that the distance from the pivot pins 118 and 120 to the meshing gear segments 112 and 114 is somewhat less than the distance from the pivot pins to the rollers 102 and 104. The relatively large distance from the pivot pins 118 and 120 to the rollers 102 and 104 results in an arcuate sweeping movement of the rollers from the open position to the closed position. This sweeping movement prevents pieces of solid material from being caught between the rollers 102 and 104. It will be apparent to those skilled in the art that if solid material was caught between the rollers 102 and 104 the flexible conduit section 100 would soon be worn and punctured.

The valve assembly 36 is substantially similar in construction to the valve assembly 30 and includes a pair of pivotally mounted third class levers 124 and 126 which are pivoted by a piston and cylinder assembly 130 from the open position shown to the closed position. Since the valve assembly 36 is substantially similar to the valve assembly 30, it is believed that further explanation of the construction of the valve assembly 36 is not required at this time.

The double-acting piston and cylinder assemblies 110 and 130 are connected to a suitable control valve mechanism, of known construction, which coordinates the operation of the cylinders -110 and 130 with the operation of the double-acting piston and cylinder assemblies 44. This coordination of the operation of the piston and cylinder assemblies 44, 110 and 130 results in the valve assembly 30 being closed, as shown, when the piston and cylinder assembly 44 is operated to apply fluid pressure against the bladder 60. Of course, the valve assembly 36 is open when iiuid pressure is applied against the bladder so that materials can be expelled from the chamber 62 of the bladder through the valve assembly 36. After the materials have been expelled from the bladder in the manner previously explained, the valve assembly 36 is closed and the valve assembly 30 is opened to enable materials to be drawn into the central chamber of the bladder 62 while preventing a reverse or downstream iiow of the materials which were previously expelled from the bladder.

The operation of the pump assembly 20, constructed as illustrated in FIGS. 1 through l5, will be largely apparent from the foregoing description. However, it should be noted that the pump assembly 20 contemplates the use of a bladder 60 having a relatively flexible input portion and a relatively inflexible output portion so that the bladder is moved from the initial position to the collapsed position with a wave which moves from the relatively flexible input end portion of the bladder toward the relatively inflexible output portion of the bladder. After the bladder 60 has been emptied, the valve assembly 36 is closed and the valve assembly 30 is opened. The double-acting hydraulic piston and cylinder assemblies 44 are then operated to withdraw uid from the body section 26 of the pump assembly to expand the bladder outwardly with a wavetype movement which will extend from the relatively inexible output end portion of the bladder toward the relatively iiexible input end portion 86 of the bladder. Repetitive collapsing and expanding of the bladder 60 results in a diastolic action which pumps fluids upstream.

Although valve assemblies 30 and 36, constructed as previously explained, are preferred, it will be apparent to those skilled in the art that other known types of valve assemblies can, if desired, be used. It will also be apparent to those skilled in the art that the requisite flexibility characteristics of the bladder 60 can be obtained by structures other than the three illustrated embodiments. For example, it is contemplated that ribs having a uniform cross-section could be used with a relatively large number of ribs being provided at the output end portion of a bladder and a relatively small number of ribs being provided at the input end portion of the bladder. Of course, many combinations of the disclosed embodiments of the invention can be formed. Therefore, while particular embodiments of the invention have been shown, it should be understood, of course, that the invention is not limited thereto since many modifications may be made; and it is contemplated to cover by the appended claims any such modifications as fall within the true spirit and scope of the invention.

What is claimed is:

1. A pump assembly comprising: a rigid elongated shell; a flexible bladder positioned within 4and extending longitudinally of said shell, said bladder having side walls at least partially defining a central material receiving charnber which is open at first and second opposite longitudinal end portions to enable materials to enter the chamber through an opening in the first end portion of said bladder and to be expelled from the chamber through an lopening in the second end portion of said bladder; a rigid liner located inwardly of said shell and adjacent to an outer surface of the side walls of said bladder to form a passage -means extending around said 'bladder to provide a channel between said liner and said shell for a liow of iiuid from a source of fluid under pressure, said liner including a plurality of apertures through which fluid from said source of iiuid under pressure ows to engage the outer surface of the side walls yof said bladder to urge said bladder inwardly from a normal position to a collapsed position to force material from the central charnber of said bladder; yand a plurality of reinforcing ribs connected -with and extending longitudinally of the side wall of said bladder, said ribs being formed to have a relatively `small resistance to inward bending near the first end portion of said bladder and a relatively large resistance to bending near the second end portion of said bladder, whereby increasing fluid pressure against the side walls of said bladder causes the first end portion of said bladder to move from the normal position to the collapsed position Ibefore the second end portion of said bladder moves from the normal position to the collapsed position to force material within the central chamber of the bladder from the first end portion of the bladder toward the second end portion of the bladder and out the opening in the second end portion of the bladder.

2. A pump assembly as set forth in claim 1 further including: a first valve means mounted adjacent to the first end portion of said bladder for controlling a flow of material through the opening in the first end portion of said bladder; and a second valve means mounted adjacent to the second end portion of said bladder for controlling a flow of material through the opening in the second end portion of said bladder, said first valve means being closed and said second valve means being open when said bladder is moved from the normal position to the collapsed position to allow material to flow out of the central chamber in said bladder through only the opening in the second end portion of said bladder, said first valve means being open and said second valve means being closed when said bladder is moved from the collapsed position to the normal position to allow material to flow into the central chamber in said bladder through only the opening in the first end portion of said bladder.

3. A pump assembly as set forth in claim 2 wherein: each of said first and second valve assemblies includes a flexible conduit section mounted with a central passage in fluid communication with the central chamber of said bladder, first and second members mounted on opposite sides of said flexible conduit section, and hydraulic means for moving said first and second members toward each other to constrict the central passage in the fiexible conduit section to close the valve assembly.

4. A pump assembly as set forth in claim 3 further including: first and second pivotally mounted levers connected to said first and second members respectively and to said hydraulic means, said first and second levers being pivoted by said hydraulic means to move said first and second members along arcuate paths toward each other to close the valve assembly.

S. A pump assembly as set forth in claim 4 further including: gear means connected to said rst and second levers for coordinating the movement of said first and second levers and for transmitting d-rive forces between said first and second levers to move said first and second members contemporaneously inwardly to close the valve assembly.

6. A pump assembly as set forth in claim 1 wherein: said ribs have a relatively small cross-sectional area adjacent to the first end portion of said bladder and a relatively large cross-sectional area adjacent to the second end portion of said bladder, where-by said ribs have the greatest resistance to bending adjacent to the second end portion of said bladder.

7. A pump assembly as set forth in claim 1 wherein: said ribs are connected to spring elements mounted adjacent to the second end portion of said bladder, whereby said ribs have the greatest resistance to bending adjacent to the second end portion of said bladder.

'8. A pump assembly as set forth in claim 7 wherein: said spring elements are imbedded in said ribs.

9. A pump assembly comprising: a rigid elongated shell; a fiexible bladder positioned within and extending longitudinally of said shell, said bladder having side Walls at least partially defining a central material receiving chamber which is open at first and second opposite longitudinal end portions to enable material to enter the chamber through an opening in the first end portion of said bladder and to be expelled from the chamber through an opening in the second end portion of said bladder; and a rigid liner located inwardly of said shell and adjacent to an outer surface of the side wall of said bladder to form a passage means extending around said bladder to provide a channel between said liner and said shell for a flow of fluid from a source of fiuid under pressure, said liner including a plurality of apertures through `which fluid from said source of fluid under pressure flows to engage the outer surface of the side `wall of Said 'bladder to urge said bladder inwardly from a normal position to a collapsed position to force material from the central chamber of said bladder, the walls of said bladder having a first relatively small thickness adjacent to the first end portion of said bladder and a second relatively large thickness adjacent to the second end portion of said bladder, whereby increasing fiuid pressure against the side wall of said bladder causes the first end portion of said bladder to move from the normal position to the collapsed position before the second end portion of said bladder moves from the normal position to the collapsed position to force material `within the central chambers out of the bladder from the first end portion of the bladder towards the second end portion of the `bladder and out the opening in the second end portion of the bladder.

10. A pump assembly comprising: a longitudinally extending rigid shell; a flexible bladder mounted within said shell, said bladder including a longitudinally extending side wall at least partially defining a central chamber for receiving materials, said bladder being relatively flexible adjacent to a first end portion of said bladder and relatively inflexible adjacent to a second end portion of said bladder; and hydraulic means connected to said shell for applying fluid pressure against an outer surface of the side wall of said bladder to move said 4bladder from an initial position to a collapsed position, the relatively flexible first end portion of said bladder being moved to the collapsed position before the relatively infiexible second end portion of said bladder to force material within the central chamber of said bladder from the first end portion of said bladder and out an opening in the second end portion of said bladder.

11. A pump assembly as set fort-h in claim 10 further including: a first valve means mounted adjacent to the first end portion of said bladder for controlling a flow of material through an opening in the first end portion of said bladder; and a second valve means mounted adjacent to the second end portion of said bladder for controlling a flow of material through the opening in the second end portion of said bladder, said first valve means being closed and said second valve means being open when said bladder is moved from the initial position to the collapsed position to allow material to flow out of the central chamber in said bladder through only the opening in the second end portion of said bladder, said first valve means being open and said second valve means being closed when said bladder is moved from the collapsed position to the normal position to allow material to flow into the central chamber in said bladder through only the opening in the first end portion of said bladder.

12. A pump assembly as set forth in claim 11 wherein: the side wall of said lbladder includes a plurality of longitudinally extending ribs having a relatively small crosssectional area adjacent to the first end portion of the bladder and a relatively large cross-sectional area adjacent the second end portion of said bladder.

13. A pump assembly as set forth in claim 11 wherein: said bladder has a relatively thin side ywall adjacent to the first end portion of said bladder and a relatively thick side wall adjacent to the second end portion of said bladder.

14. A pump assembly as set forth in claim 11 wherein: said bladder includes a plurality of spring members mounted adjacent to the second end portion of said bladder.

15. A pump assembly as set forth in claim 14 wherein: said spring members are embedded in ribs which extend longitudinally of said bladder.

16. A pump assembly as set forth in claim 10 further including: a plurality of springs mounted between said bladder and said shell for holding said bladder against collapsing.

17. A pump assembly as set forth in claim 16 wherein: said springs are mounted in spring groups including a rst spring group mounted adjacent to the rst end portion of said bladder, a second spring group mounted between the rst spring ygroup and the second end portion of said bladder, said second spring group including a larger number of said springs than said rst spring group.

18. A pump assembly as set forth in claim 16 wherein: said springs have dierent exibility characteristics with relatively flexible springs bein-g mounted adjacent to the iirst end portion of said bladder and relatively inflexible springs being mounted adjacent to the second end portion of said bladder.

19. A pump assembly as set forth in claim 16 wherein: said springs are imounted relatively far apart adjacent to the )firstk end portion of said bladder and relatively close l2 together adjacent to the second end portion of said bladder.

References Cited UNITED STATES PATENTS 2,604,246 7/1952 Hood 103--148 2,747,510 5/ 1956 Von Seggern 10B-148 2,760,436 8/1956 Von Seggern -103--148 2,814,993 12/1957 Schmidt 103-148 2,884,866 5/1959 Patterson 10S-148 3,062,153 11/1962 Losey 103-148 3,359,916 12/1967 Houston et al 103-148 DONLEY J. STOCKING, Prmaiy Examiner.

WILBUR J. GOODLIN, Assistant Examiner. 

